recordmcount: Correct st_shndx handling

One should only use st_shndx when >SHN_UNDEF and <SHN_LORESERVE. When
SHN_XINDEX, then use .symtab_shndx. Otherwise use 0.

This handles the case: st_shndx >= SHN_LORESERVE && st_shndx != SHN_XINDEX.

Link: https://lore.kernel.org/lkml/20210607023839.26387-1-mark-pk.tsai@mediatek.com/
Link: https://lkml.kernel.org/r/20210616154126.2794-1-mark-pk.tsai@mediatek.com
Reported-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[handle endianness of sym->st_shndx]
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index f9b1952..1e9baa5 100644 (file)
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -192,15 +192,20 @@ static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab,
                                 Elf32_Word const *symtab_shndx)
 {
        unsigned long offset;
+       unsigned short shndx = w2(sym->st_shndx);
        int index;
 
-       if (sym->st_shndx != SHN_XINDEX)
-               return w2(sym->st_shndx);
+       if (shndx > SHN_UNDEF && shndx < SHN_LORESERVE)
+               return shndx;
 
-       offset = (unsigned long)sym - (unsigned long)symtab;
-       index = offset / sizeof(*sym);
+       if (shndx == SHN_XINDEX) {
+               offset = (unsigned long)sym - (unsigned long)symtab;
+               index = offset / sizeof(*sym);
 
-       return w(symtab_shndx[index]);
+               return w(symtab_shndx[index]);
+       }
+
+       return 0;
 }
 
 static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)